Hydropneumatic suspension unit as well as hydropneumatic suspension system

ABSTRACT

A hydropneumatic suspension system arranged on a bogie for a vehicle, particularly for a rail vehicle, and one hydropneumatic suspension unit respectively which is contained in the suspension system. For this purpose, the spring accumulator, the reservoir, the tank and the control unit are arranged in the area of the at least one spring strut, so that an essentially self-sufficient suspension unit is obtained. The suspension system may be used and connected to a levelling unit.

BACKGROUND AND SUMMARY OF THE INVENTION

[0001] The invention relates to a hydropneumatic suspension unit for avehicle, particularly a rail vehicle. The invention also relates to ahydropneumatic suspension system which has at least two suspension unitsof this type, and to a bogie.

[0002] In such suspension systems, the required hydraulic supply andcontrol unit is disposed either in or on the bogie of a car body and isconnected with at least one spring strut per body side, or it isarranged on the car body and supplies the spring struts of severalbogies. In this case, the spring struts of the two car body sides of abogie are connected with one another by one overflow valve respectively.The valve is always closed in normal operation and opens only when thepressure in one of the two spring struts drops in an unacceptablyexcessive manner, for example, as a result of a line snapping. Thus, itis ensured thereby that the vehicle is lowered to a defined emergencysupport without taking up an inclined position which, as a. rule, doesnot permit the operation of the vehicle. This overflow function isnormally implemented by a valve arrangement on the control plate which,however, requires a high-expenditure tubing of the components of thesuspension system distributed in the bogie or in the car body.

[0003] An example of such a hydropneumatic suspension system is knownfrom International Patent Document WO 94/08833. The arrangementillustrated here is used specifically for the level and inclinationcontrol of a car body of a rail vehicle, in which case thehydropneumatic suspension has to be capable of controlling a relativelyhigh ratio of the vehicle weights in the fully loaded or emptycondition. In addition, this known construction relates to the problemthat the vehicle level has to be kept at least approximately constantalso during a change of passengers at stops.

[0004] This system is therefore based particularly on the problem thatthe levelling has to be carried out at a high speed; that is, largeamounts of oil can be fed into the hydraulic circuits of the suspensionand can be discharged from them respectively in a relatively short time.This problem is solved in that, when a correction requirement isrecognized with respect to the level or inclination of the car body, apump operates directly against the pressure of the hydropneumatic springaccumulator of the suspension damping system and pressure medium will beremoved from the reservoir filled during the travel only when thedelivery volume of the pump is not sufficient for keeping the level ofthe car body constant. In particular, as a result, the energyconsumption of the overall system is minimized.

[0005] In order to be able to minimize the size of the units, thesehydropneumatic suspension systems or control circuits exist in thevehicle several times, in which case each side may comprise only one orseveral spring struts. The spring struts of the left and rightsuspension are hydraulically connected with one another, so thatone-sided lowerings or lifts of the vehicle can be corrected byoverflowing hydraulic fluid.

[0006] However, such distributed systems for a hydropneumatic suspensiongenerally require a high-expenditure casing of the componentsdistributed in the bogie or in the car body. This casing results in highcosts; its laying in the bogie is difficult; and there is the dangerthat the hydraulic system of the hydropneumatic suspension iscontaminated by dirt in the lines which may result in an impairment ofits functioning. It is another disadvantage that, as a result of theunavoidable relative movements between the individual components on thebogies and the car body as well as between components at differentinstallation sites on the bogie, there is the danger of damage to theline elements and a possible leakage. This may result in a loss of theoperability of the entire system.

[0007] It is therefore an object of the present invention to furtherdevelop a hydropneumatic suspension unit for a vehicle, particularly arail vehicle, or a hydropneumatic suspension system such that the casingexpenditures can be reduced.

[0008] This object is achieved by a hydropneumatic suspension unit ofthe present invention.

[0009] It was recognized according to the invention that the casingexpenditures can be reduced by a meaningful arrangement of the partscomponents in the direct proximity of the spring strut. As a result, atype of self-sufficient suspension unit can be achieved which suppliesin each case only one or several spring struts on one side of the carbody of the bogie. This leads to a very compact construction whosecomponents are subjected to essentially no relative movements withrespect to one another. These can therefore be directly coupled to oneanother, which significantly simplifies the construction and reduces thedanger of damage as a result of the dynamic movement of the vehicle whentravelling.

[0010] The suspension unit according to the invention is thereforedistinguished by low mounting expenditures and high reliability.

[0011] As a special embodiment of the suspension unit according to theinvention, the spring accumulator, the reservoir, the tank and thecontrol unit may be arranged on both sides of a spring strut axis. Thisresults in a construction which is compact and continues to be easilyaccessible with respect to the individual components, which facilitatesthe mounting as well as the servicing.

[0012] As an alternative construction, the spring accumulator, thereservoir, the tank and the control unit may also be arranged in a starshape around the at least one spring strut, so that all components arepresent as closely as possible around the spring strut axis. This verycompact construction can therefore even better withstand the dynamicstresses occurring during the travel. In addition, the spacerequirements for the arrangements can be minimized thereby.

[0013] As an additional alternative construction of the spring unitaccording to the invention, the spring accumulator and the reservoir canbe arranged directly at the at least one spring strut, while the tankand the control unit are arranged adjacent thereto at the bogie and areconnected by a connection line with the at least one spring strut. Thistwo-part solution has the advantage that the spring system can bemanipulated better for the mounting. In addition, the control unit canbe mounted at low expenditures for servicing work, particularly withouthaving to remove the spring strut.

[0014] According to another aspect of the invention, a hydropneumaticsuspension system is provided, which has at least two suspension unitsaccording to the invention which are arranged on both sides on the carbody of the vehicle, and, in addition, contains a levelling unit whichis assigned to the at least two suspension units.

[0015] The suspension unit according to the invention thereby alsoutilizes the advantage that a casing within the suspension units willnot be necessary. As a result, a very simple modular construction of thesuspension system can be achieved which significantly simplifies themounting. As will be explained in detail in the following, the levellingunit can in this case also be connected without casing expenditures withthe suspension units, thereby permitting a constructively particularlysimple and very reliable construction.

[0016] Thus, it is, for example, possible that the levelling unit isarranged separately of the at least two suspension units on the bogie oron the car body. The levelling unit will then constitute a separatemodule which is easy to mount. In addition, the suspension units may beprovided as identically designed modules.

[0017] As an alternative, it is possible to assign the levelling unit toa suspension unit, whereby the installation expenditures for theconnection lines can be reduced as a whole. Furthermore, no additionaldevices are required for the fastening of the levelling unit on thebogie or on the car body so that the construction is simplified.

[0018] In this case, the levelling unit can be electronically coupledwith the at least two suspension units. In this manner, an overflowfunction can be implemented without any casing expenditures. Thus, apurely electronic pressure monitoring of the system pressure can takeplace in the two levelling circuits. Thus, when a previously adjusteddifferential pressure is exceeded, an electrically actuated drain valveor the like is actuated and thus provides the required pressurecompensation. Such a drain valve can already be provided in thelevelling unit. In addition, for detecting the pressure in the twosuspension units, one electric pressure sensor respectively can beutilized, for example, for the electric load detection. This solutionrequires a pressure detection of the respective other side by thehydraulic medium itself, because here only signal cables are requiredbetween the suspension units. This construction can therefore beimplemented at low mounting expenditures and is distinguished by highreliability.

[0019] As an alternative, it is also possible for the levelling unit tohave one differential-pressure control valve respectively for eachsuspension unit, the differential-pressure control valves being mutuallyconnected by pressure gauge lines. A pressure compensation is thereforepermitted between two or more self-sufficient suspension units, withoutthe requirement of a fluid mass flow. In this case, such adifferential-pressure control valve opens up starting from an adjusteddifferential pressure between the two suspension units and drains oilfrom the levelling circuit into the tank of the respective unit untilthe differential pressure has again reached its predetermined amount. Inthis case, the oil quantity in each suspension unit does not change,which is why a tank connection line between the two suspension units isnot required. This results in very low casing expenditures because theat least two required connection lines between the car sides can beimplemented by the pressure gauge line. These have clearly smallerdimensions than hydraulic lines and can be laid at lower expendituresthan such hydraulic pipes or hydraulic hoses. In addition, they have amore flexible design, so that the mounting is further simplified.

[0020] Furthermore, it is also possible that the levelling unit has onedifferential-pressure control valve for each suspension unit, thedifferential-pressure control valves being connected with the suspensionunits by hydraulic lines, and the tanks of the at least two suspensionunits also being connected with one another by a hydraulic line. Despitethe required two hydraulic lines, this construction is also stilldistinguished by essentially reduced casing expenditures in comparisonto the prior art because the casing expenditures are clearly reduced asa whole as a result of the decentralization of the suspension units.

[0021] According to another embodiment of the invention, it is alsopossible that the levelling unit has in each case onedifferential-pressure control valve respectively for each suspensionunit. In this case, each differential-pressure control valve isconnected by a hydraulic line with a suspension unit on the other carbody side, and the tanks of the at least two suspension units areconnected with one another also by a hydraulic line. As a result, theparts components of the system can essentially be integrated in thesuspension units, in which case they can, in addition, have anessentially identical construction. The expenditures for providing thesuspension system can be significantly reduced thereby. In addition,clearly lower casing expenditures can thereby be achieved in comparisonto the prior art because the individual components are combined insuspension units.

[0022] According to another aspect of the invention, a bogie is providedwhich has such a suspension unit or such a suspension system. Because ofthe compact construction of the components, the bogie according to theinvention is distinguished by particularly low mounting expenditures. Inaddition, it can be provided at reasonable cost and has a highreliability and service life, in which case the servicing expenditurescan also be minimized.

[0023] Other objects, aspects and novel features of the presentinvention will become apparent from the following detailed descriptionof the invention when considered in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 is a simplified perspective representation of a bogiehaving a hydropneumatic suspension system according to the invention,individual components being omitted for the purpose of clarity;

[0025]FIG. 2 is a perspective view of a suspension unit according to theinvention in a first embodiment;

[0026]FIG. 3 is a view of a suspension unit according to the inventionaccording to a second embodiment;

[0027]FIG. 4 is a schematic operational diagram of a first embodiment ofthe suspension system according to the invention;

[0028]FIG. 5 is a schematic operational diagram of a second embodimentof the suspension system according to the invention;

[0029]FIG. 6 is a schematic operational diagram of a third embodiment ofthe suspension system according to the invention;

[0030]FIG. 7 is a schematic operational diagram of a fourth embodimentof the suspension system according to the invention; and

[0031]FIG. 8 is a schematic operational diagram of a fifth embodiment ofthe suspension system according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] According to the representation in FIG. 1, a suspension system inthis embodiment has two suspension units 2 each mounted on a frame on abogie 1 of the vehicle. In this case, the suspension system is used fordamping shocks and vibrations of the bogie 1 with respect to the carbody of the vehicle which is not shown here and which is arranged abovethe suspension units 2.

[0033] The active axis of each suspension unit 2 is arrangedperpendicular to the wheel axes of the bogie 1. The two suspension units2 jointly support the car body at a line which is not shown and whichconnects the upper ends of the suspension units 2 and is situatedparallel to the wheel axes. In this case, the suspension system issituated essentially in the center between the wheel axes of the bogie1. In addition, each suspension unit 2 is arranged outside therespective wheel disk of the bogie 1, an arrangement in the wheel diskplane also being possible.

[0034] As illustrated in the detail in FIG. 2, each suspension unit 2has a carrier or manifold 21 on which a spring strut 22, a springaccumulator 23, a reservoir 24, a control unit 25 and a tank 26 arefastened. The control unit 25 has an electric motor 251, an electroniccontrol module 252 and valve or pressure transducing units 253. Thesecomponents are essentially coupled directly to one another through thecarrier or manifold 21 so that no casing expenditures are requiredbetween the latter. For the purpose of completeness, it should also bepointed out that the suspension unit 2 also has additional valves, levelsensors, a hydraulic pump etc. as well as a covering, which are notshown here. The level sensor may be integrated, for example, into thesuspension unit 2 or may be mounted externally. As illustrated in FIG.2, the parts components of the suspension unit 2 are arranged on bothsides of the spring strut axis.

[0035]FIG. 3 shows a modified construction in which a suspension unit 2′is essentially divided into two parts units. On the one hand, the springstrut 22 with the directly flanged-on spring accumulator 23 and thereservoir 24 form a unit on carrier 21A; while the control unit 25 andthe tank 26 are provided separately thereof on carrier 21B. A connectionline 27 is used as the connection between carrier 21A and 21B which,however, according to the representation, may have a very short lengthbecause, in addition, all components are arranged in the area of thespring strut 22. In this case, the connection line 27 is shown as ahydraulic hose.

[0036]FIG. 4 is a schematic operational diagram of a first embodiment ofthe suspension system according to the invention. In addition to the twosuspension units 2, level sensors 4 assigned to each suspension 2 and ajoint levelling unit 5 are provided. The level sensors 4 supplycorresponding information to the levelling unit 5 which, in turn, emitsa control signal to the control unit 25 of each suspension unit 2. Here,the levelling unit 5 can be centrally arranged on the bogie 1, on or inthe car body or it can also be assigned to a suspension unit 2. By thisconstruction, an overflow function can be implemented without any casingexpenditures because a purely electronic pressure monitoring of thesystem pressure can take place in the two levelling circuits. In thiscase, when a differential pressure, which is preferably adjusted withrespect to the software, is exceeded, an electrically controlled drainvalve is actuated which, as a rule exist for each unit, whereby therequired pressure compensation becomes possible. For detecting thepressure in the two suspension units 2, one electric pressure sensorrespectively is provided which can be utilized, for example, also forthe electric load detection. Thus, no pressure detection of therespective other side is required by way of a hydraulic medium, since inthis construction there are only signal cables between the suspensionunits. The installation expenditures for the required signal cables canbe further reduced if the levelling unit 5 is assigned to one of thesuspension units 2 or is integrated therein.

[0037]FIG. 5 illustrates second embodiment of the suspension systemaccording to the invention in which the levelling unit 5 has twodifferential-pressure control valves 51 and 52 which are assigned to therespective suspension units 2. Each differential-pressure control valve51 and 52 respectively is connected with the other suspension unit 2 bya pressure gauge line or mini gauge line, so that it is provided withthe pressure level of this levelling circuit. Starting from a previouslyset differential pressure between the two suspension units 2, therespective differential-pressure control valve 51 or 52 respectivelywill open up and will drain oil from the respective levelling circuitinto the tank 26 of the suspension unit 2, until the differentialpressure again falls below the predetermined limit value. Here, the oilquantity in the suspension system cannot change. Since only two pressuregauge lines are used for the two connection lines between the car bodysides, casing expenditures can essentially be avoided. Such pressuregauge lines have significantly smaller dimensions than hydraulic tubelines or hydraulic hoses and can be laid in an easier or more flexiblemanner. A pressure adjustment is by an offset signal which istransmitted by an upright oil pressure column, which is closed initself, in a pressure gauge line from one differential-pressure sensorto another differential-pressure sensor of the differential pressurecontrol valves. Thus, no pressure compensation takes place by a fluidmass flow.

[0038]FIG. 6 illustrates a third embodiment of the suspension systemaccording to the invention, here the two differential-pressure controlvalves 51 and 52 being arranged as a separate unit on the bogie 1 or onthe car body. In addition, this construction has one hydraulic linerespectively from the levelling unit 5 to the suspension units 2.Another hydraulic line connects the tanks 26 of the suspension units 2with one another in order to prevent an unacceptably high amount of oilon one car body side in the event of an overflow of oil.

[0039] According to FIG. 7, the differential-pressure control valves 51and 52 in a fourth embodiment can also be assigned to a suspension unit2, so that they are not present as a separate module.

[0040] In a fifth embodiment of the present invention according to FIG.8, the differential pressure control valves 51 and 52 may also each beassigned to the suspension units 2. An additional hydraulic line willthen be required in order to form the levelling circuit.

[0041] In addition to the embodiments indicated here, the inventionpermits additional design principles.

[0042] Thus, some of the components of the electric control unit 25 oradditional electric components may be arranged on the bogie 1 or on thecar body, the control unit 25 interacting with these components. As aresult, the stress on one portion of the electric components can bereduced within certain limits.

[0043] In addition, it is possible to arrange the spring accumulator 23,the reservoir 24, the tank 26 and the control unit 25 in a star-shapedmanner around the respective spring strut 22.

[0044] Also, when larger loads are to be absorbed, two or several springstruts 22 can be arranged directly side-by-side, which are then suppliedor controlled by a common spring accumulator 23, reservoir 24, tank 26or a joint control unit 25. Furthermore, spring struts 22 which arearranged on one side of the vehicle in a mutually spaced manner can alsobe serviced by joint supply and control components.

[0045] When the levelling unit 5 is arranged on the car body or on thebogie 1, it can also control more than two suspension units 2 arrangedlaterally on the vehicle.

[0046] The invention thus provides a hydropneumatic suspension systemfor a vehicle, particularly for a rail vehicle, and a hydropneumaticsuspension unit respectively which is contained in the suspensionsystem, and by means of which the casing expenditures for the suspensionsystem can clearly be reduced. As a result, the mounting and themaintenance of the system can be significantly simplified.

[0047] Although the present invention has been described and illustratedin detail, it is to be clearly understood that the same is by way ofillustration and example only, and is not to be taken by way oflimitation. The spirit and scope of the present invention are to belimited only by the terms of the appended claims.

1. A hydropneumatic suspension unit for use on a rail vehicle between a bogie and a car body of the rail vehicle, the unit comprising: a spring accumulator, a reservoir; at least one spring strut; a tank; a control unit for controlling the level of the at least one spring strut; and wherein the spring accumulator, the reservoir, the tank and the control unit are arranged in the area of the at least one spring strut.
 2. The hydropneumatic suspension unit according to claim 1, wherein the spring accumulator, the reservoir, the tank and the control unit are arranged on both sides of a spring strut axis.
 3. The hydropneumatic suspension unit according to claim 1, wherein the spring accumulator, the reservoir, the tank and the control unit are arranged in a star-shaped manner around the at least one spring strut.
 4. The hydropneumatic suspension unit according to claim 1, wherein the spring accumulator and the reservoir are connected directly on the at least one spring strut, while the tank and the control unit are arranged adjacent thereto on the bogie or on the car body and are connected by a connection line with the at least one spring strut.
 5. The hydropneumatic suspension unit according to claim 1, wherein the spring accumulator, the reservoir, the tank and the control unit are connected directly on the at least one spring strut.
 6. A hydropneumatic suspension system for a rail vehicle, comprising; at least two suspension units according to claim 1, which are arranged on both sides on the car body of the vehicle; and a levelling unit coupled with the at least two suspension units.
 7. The hydropneumatic suspension system according to claim 6, wherein the levelling unit is located separate from the at least two suspension units on the bogie or on the car body.
 8. The hydropneumatic suspension system according to claim 6, wherein the levelling unit is located with one of the suspension units.
 9. The hydropneumatic suspension system according to claim 6, wherein the levelling unit is electronically coupled with the at least two suspension units.
 10. The hydropneumatic suspension system according to claim 6, wherein in that the levelling unit has one differential-pressure control valve respectively for each suspension unit, and the differential-pressure control valves are mutually connected by pressure gauge lines.
 11. The hydropneumatic suspension system according to claim 6, wherein the levelling unit has one differential-pressure control valve respectively for each suspension unit; the differential-pressure control valves are connected with the suspension units by hydraulic lines; and the tanks of the at least two suspension units are connected with one another by way of a hydraulic line.
 12. The hydropneumatic suspension system according to claim 5, wherein the levelling unit, for each suspension unit, has one differential-pressure control valve respectively assigned to the respective suspension unit, each differential-pressure control valve is connected by a hydraulic line with a suspension unit on the other car body side; and the tanks of the at least two suspension units are connected with one another by a hydraulic line.
 13. A bogie for a rail vehicle including a hydropneumatic suspension system according to claim
 6. 